1. Field of the Invention
The invention concerns air conditioning systems, in particular for automobile vehicles.
2. Description of the Related Art
An air conditioning system of this type is provided with an air conditioning circuit primarily comprising a compressor, a condenser or a gas cooler, an expansion device and an evaporator, which are passed through, in this order, by a refrigerant fluid.
The compressor compresses the refrigerant fluid in order to bring it to an elevated pressure, then passes it on to the condenser, where it is cooled. In the expansion device, the refrigerant fluid is expanded so as to lower its pressure. The low pressure fluid then passes through the evaporator so that it is vaporized before going back into the compressor. A flow of air traversing the evaporator is cooled or air conditioned and is sent to the passenger compartment of an automobile vehicle.
Using an electronic expansion valve as an expansion device is particularly well known, in order to control the rate of fluid expanded.
In such an expansion valve, the degree of opening is regulated by a control signal adjusted as a function of certain working parameters.
For example, regulating the passage section of an electronic expansion valve as a function of a measurement of pressure and temperature, provided by a sensor placed at the outlet of the evaporator, is well known. However, pressure based sensors of the type used upon exit from the evaporator are expensive.
More generally, well-known systems do not permit optimizing the degree of opening of the electronic expansion valve as a function of the working conditions of the air conditioning and they utilize a significant number of sensors, thereby considerably increasing the overall cost of the system. Moreover, such systems require the establishment of sensors at different points, which consequently makes these systems more complex and cumbersome.